This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A112291 #14 Jun 03 2022 01:28:08
%S A112291 1,1,3,42,150,36270,270900,9440379900,3332912051700,
%T A112291 2004302168707167000,1424191116445997823000,
%U A112291 3936008766237071969447818200,10888542544398564939894000,3606055788316324023953497288103040
%N A112291 Denominator of sum{k=1 to n} 1/S(n,k), where S(n,k) is a Stirling number of the second kind.
%H A112291 Vaclav Kotesovec, <a href="/A112291/b112291.txt">Table of n, a(n) for n = 1..49</a>
%e A112291 a(4) = 42, the denominator of 1/1 + 1/7 + 1/6 + 1 = 97/42.
%e A112291 The first few fractions are: 1, 2, 7/3, 97/42, 331/150, 77089/36270, 562609/270900.
%p A112291 with(combinat): a:=n->denom(sum(1/stirling2(n,k),k=1..n)): seq(a(n),n=1..15); # _Emeric Deutsch_, Sep 02 2005
%t A112291 f[n_] := Sum[1/StirlingS2[n, k], {k, n}]; Table[Denominator[f[n]], {n, 15}] (* _Ray Chandler_, Sep 02 2005 *)
%Y A112291 Cf. A112290.
%K A112291 nonn,frac
%O A112291 1,3
%A A112291 _Leroy Quet_, Sep 01 2005
%E A112291 Extended by _Emeric Deutsch_ and _Ray Chandler_, Sep 02 2005